<mat-form-field class="grow form-field" color="accent">
  <mat-label>{{ label }}</mat-label>
  <mat-select [formControl]="control" [compareWith]="compareWith">
    <mat-option [value]="null"></mat-option>
    <mat-option *ngFor="let policy of policies" [value]="policy">
      {{ policyId(policy) }}
    </mat-option>
  </mat-select>
</mat-form-field>
